Atomic layer deposition method and semiconductor device fabricating apparatus having rotatable gas injectors

ABSTRACT

The present invention discloses an ALD method including: respectively loading a plurality of substrates into a plurality of reaction cells, the plurality of reaction cells being disposed in a reaction chamber isolated from an exterior condition; alternately and repeatedly applying various vapor substances onto each substrate such that a thin film is formed on each substrate, wherein a plurality of vapor injection pipes each injecting one of the vapor substances periodically scans over each substrate to apply the various vapor substances alternately and repeatedly onto each substrate.  
     In another aspect, the present invention discloses a semiconductor device fabricating apparatus including: a plurality of susceptors on which the same number of substrates are respectively mounted; a reaction chamber isolating all the substrates on the plurality of susceptors from an exterior condition; a plurality of vapor injection pipes disposed over the substrates, each vapor injection pipe relatively rotating with respect to the substrates and periodically applying a vapor substance onto each substrate; a plurality of exhausting portion each disposed near a corresponding susceptor to exhaust a remaining vapor substance out of the reaction chamber.

[0001] This application claims the benefit of Korean Patent ApplicationsNo. 2000-46216 filed on Aug. 9, 2000, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an atomic layer deposition (ALD)method and a semiconductor device fabricating apparatus having improvedprocessing time.

[0004] 2. Discussion of the Related Art

[0005] Electric devices are recently highly integrated to have smallersize including the vertical dimension. Specifically, a dielectric layerof a memory capacitor for a dynamic random access memory (DRAM) deviceand a gate insulating layer of a thin film transistor (TFT) device aredeveloped to be thinner and thinner in the vertical dimension.

[0006] Under the design rule of 0.13 μm or less, new materialssubstitute for conventional ones to satisfy new electric qualities fordevices fabricated under the same design rule. For example, instead of aheat-treated oxide film (usually, a silicon oxide film heat-treatedunder oxygen condition), a high dielectric film made of Al₂O₃, HfO₂,ZrO₂, or the like is selected for the above-mentioned gate insulatinglayer. For the dielectric layer of the DRAM, instead of a siliconnitride film formed by a chemical gas phase deposition, a very thin filmmade of a high dielectric compound such as barium-strontium-titanate(BST) or lead-zirconium-titanate (PZT) is selected.

[0007] A metal organic chemical vapor deposition (MOCVD) method wasconventionally applied to fabricate the conventional thin filmsincluding silicon oxide or silicon nitride. However, because the MOCVDmethod is not suitable for fabricating the new thin films including BSTor the like and having a thickness of about 100 Å (angstrom), newmethods are developed. An atomic layer deposition (ALD) method is atypical example of the new methods.

[0008] In the MOCVD, various vapor substances are simultaneously appliedto a substrate and deposited thereon to form a thin film. In the ALDmethod, however, various vapor substances are alternately and repeatedlyapplied to a substrate such that a plurality of atomic layers aresequentially deposited on the substrate to form the thin film. Recently,the ALD method is widely used to fabricate thin films of a semiconductordevice.

[0009] In case of the ALD method, the thin film grows depending on asurface chemical reaction. Accordingly, though if the substrate has anirregular shape, the thin film grows uniformly on the substrate. Inaddition, because the thin film grows in proportion not to time but tonumber of cycles each sequentially providing a group of vaporsubstances, thickness of the thin film can be controlled precisely.

[0010] In FIG. 1, a reaction chamber 100 of an ALD apparatus accordingto a related art includes a lower housing 110 a and an upper housing 110b, which provide a reaction zone 102 isolated from an exteriorcondition. Material gases are sequentially provided into the reactionzone 102 through an injection hole 140 in alternating orders. At thispoint, each material gas flows parallel to an upper surface of asubstrate 130, which is mounted on a susceptor 120 disposed in thereaction zone 102.

[0011] A conventional method of forming aluminum oxide (Al₂O₃) filmusing the above-described reaction chamber 100 was suggested in page3604, volume 71, Applied Physics Letters, 1997. In the reaction chamber100 heated at a temperature of 150° C. (.degrees. C.), the substrate 130is maintained to have a temperature of 370° C. Then, tri-methyl-aluminum[Al(CH₃)₃], purge argon (Ar), water vapor, and further purge argon (Ar)are sequentially injected into the reaction zone 102 for 1, 14, 1, and14 seconds, respectively, thereby composing a cycle. The cycle isrepeated as shown in a graph of FIG. 2. A vertical axis of the graphimplements a processing time. However, because the graph is conceptual,each period of the cycle is not proportional to its length.

[0012] The above-explained method according to the related art has someproblems.

[0013] Because the growth of the thin film is proportional to the numberof cycles, a total processing time can be shortened by shortening thetime of one cycle. However, because the conventional reaction chamberadopts valves to control the flow of each vapor substance, time delaysoccur due to a residual response time of the valves. In another aspect,after each vapor substance fills the reaction zone and reacts with thesubstrate, it is exhausted out of the reaction chamber and another vaporsubstance is injected into the reaction zone. The above-mentionedinjecting and exhausting take some time, thereby making it difficult toshorten the time of one cycle. That is to say, the growth of the thinfilm is very slow in the reaction chamber according to the related art,which means that productivity of the conventional ALD method is verylow.

[0014] In addition, in the reaction chamber according to the relatedart, the deposition occurs due to just a simple contact between thesubstrate and the vapor substance that flows parallel to the substrate.Accordingly, a deposition rate of the vapor substance is very low, whichcauses a poor productivity.

[0015] Some modifications were suggested to solve the above-explainedproblem of low productivity.

[0016] First, if a plurality of substrates, instead of just one, aremounted in the reaction zone, a simultaneous deposition can be appliedfor the plurality of substrates. Second, a plurality of reactionchambers, instead of just one, may be included in the ALD apparatus forthe same purpose.

[0017] In case of the first modification, the reaction chamber should besufficiently enlarged to contain the plurality of substrates. The largereaction chamber, however, causes a slow exhaustion of the vaporsubstance, such that a gas phase reaction of the exhausting vaporsubstance may occur in the reaction chamber.

[0018] In case of the second modification, each of the plurality ofreaction chambers should be connected with a vapor supply pipe thatprovides vapor substances. Therefore, the ALD apparatus becomes to havea complicated configuration, which causes a high cost of the ALDapparatus.

SUMMARY OF THE INVENTION

[0019] Accordingly, the present invention is directed to an ALD methodand a semiconductor device fabricating apparatus, which substantiallyobviate one or more of the problems due to limitations and disadvantagesof the related art.

[0020] An object of the present invention is to provide an improved ALDmethod and a semiconductor device fabricating apparatus implementing notime delay that results from valves thereof

[0021] Another object of the present invention is to provide an improvedALD method and a semiconductor device fabricating apparatus implementinghigh deposition rate of vapor substances.

[0022] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.The objectives and other advantages of the invention will be realizedand attained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0023] In order to achieve the above object, the preferred embodiment ofthe present invention provides an atomic layer deposition method, whichincludes: respectively loading a plurality of substrates into aplurality of reaction cells, the plurality of reaction cells beingdisposed in a reaction chamber isolated from an exterior condition;alternately and repeatedly applying various vapor substances onto eachsubstrate such that a thin film is formed 6 n each substrate, wherein aplurality of vapor injection pipes each injecting one of the vaporsubstances periodically scans over each substrate to apply the variousvapor substances alternately and repeatedly onto each substrate.

[0024] Each substrate is optionally heated using a heater disposed inthe reaction chamber.

[0025] RF power is optionally applied to the vapor injection pipes suchthat plasma is generated in the reaction chamber.

[0026] In another aspect, the present invention provides a semiconductordevice fabricating apparatus, which includes: a plurality of susceptorson which the same number of substrates are respectively mounted; areaction chamber isolating all the substrates on the plurality ofsusceptors from an exterior condition; a plurality of vapor injectionpipes disposed over the substrates, each vapor injection pipe relativelyrotating with respect to the substrates and periodically applying avapor substance onto each substrate; and a plurality of exhaustingportion each disposed near a corresponding susceptor to exhaust aremaining vapor substance out of the reaction chamber.

[0027] A vertical distance between the susceptors and the vaporinjection pipes are variable.

[0028] The apparatus optionally includes a ring-shaped heater disposedunder the plurality of susceptors to heat the substrates.

[0029] The apparatus preferably further includes a partition wallseparating each substrate from the others such that the vapor substanceapplied onto the substrate reacts with the same substrate only.

[0030] In one aspect, the plurality of susceptors are fixed and theplurality of vapor injection pipes rotate. In that case the apparatuspreferably further includes a position controller controlling therotation speed of the plurality of vapor injection pipes.

[0031] Alternatively, the plurality of vapor injection pipes are fixedand the plurality of susceptors rotate. In that case, the apparatuspreferably further includes a position controller controlling therotation speed of the plurality of susceptors.

[0032] RF power is optionally applied to the plurality of vaporinjection pipes to activate the vapor substance such that plasma isgenerated in the reaction chamber

[0033] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWING

[0034] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0035] In the drawings:

[0036]FIG. 1 is a conceptual sectional side elevation view illustratinga reaction chamber of an ALD apparatus according to the related art;

[0037]FIG. 2 is a graph illustrating repeated cycles of providing vaporsubstances for the ALD apparatus according to the related art;

[0038]FIG. 3 is a sectional side elevation view illustrating asemiconductor device fabricating apparatus according to a preferredembodiment of the present invention;

[0039]FIG. 4 is a plan view illustrating vapor supply portions of theapparatus shown in FIG. 3; and

[0040]FIG. 5 is a vertical sectional view illustrating the semiconductordevice fabricating apparatus shown in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings.

[0042] In FIG. 3, a semiconductor device fabricating apparatus 300according to the preferred embodiment of the present invention includesa reaction chamber 304. The reaction chamber 304 contains a plurality ofsusceptors 303 on which a plurality of substrates 314 are respectivelymounted. That is to say, the plurality of substrates 314 are isolatedfrom an exterior condition due to the reaction chamber 304.

[0043] A vapor supply pipe 305 penetrates into an upper portion of thereaction chamber 304 and communicates with a plurality of vaporinjection pipes 308 a to 308 d (see FIG. 4), which are disposed over thesubstrates 314 in the reaction chamber 304. Each of the vapor injectionpipes 308 a to 308 d has a plurality of open holes 307 toward thesubstrates 314. The vapor supply pipe 305 includes a plurality ofconcentric pipes (not shown) therein. Each concentric pipe has adifferent diameter depending on which vapor substance passestherethrough. The plurality of concentric pipes communicate with theplurality of vapor injection pipes 308 a to 308 d, respectively.Accordingly, the plurality of vapor injection pipes 308 a to 308 drespectively apply different vapor substances onto the substrates 314.

[0044] After the vapor substance is deposited on the substrate 314, thesame vapor substance remaining in the reaction chamber 304 is exhaustedthrough exhaust pipes 306. A plurality of ring-shaped heaters 312 areconcentrically disposed under the susceptors 303 to heat the substrates314 during the deposition.

[0045] The vapor supply pipe 305 can rotate with respect to a concentricaxis of the plurality of concentric pipes (not shown) as well as canmove in a longitudinal direction thereof. Height and rotation speed ofthe vapor supply pipe 305 are controlled by a position controller 316.Because the plurality of vapor injection pipes 308 a to 308 dcommunicated with the vapor supply pipe 305, they also rotate or movetogether with the vapor supply pipe 305. That is to say, the pluralityof vapor injection pipes 308 a to 308 d timely inject the various vaporsubstances onto the substrates 314 as they are rotating over thesubstrates 314.

[0046] At this point, each susceptor 303, a corresponding substrate 314,and one of the vapor injection pipes 308 a to 308 d are arranged in areaction cell (320 a to 320 d in FIG. 5) defined by a partition wall 310(see FIG. 5). In other words, each of the reaction cells 320 a to 320 din FIG. 5 defined by the partition wall 310 respectively contains onesusceptors 303 and a corresponding substrate 314. The injection pipes308 a to 308 d respectively injecting different vapor substances aresequentially and repeatedly positioned in each of the reaction cells(320 a to 320 d in FIG. 5). Accordingly, each different vapor substanceis applied onto each substrate 314 with a pulse interval.

[0047] For example, first to fourth vapor injection pipes 308 a to 308 din FIG. 4 are respectively injecting tri-methyl-aluminum [Al(CH₃)₃],purge argon (Ar), water vapor, and further purge argon (Ar). Then, thefirst to fourth vapor injection pipes 308 a to 308 d are rotating overthe four substrates 314 (in FIG. 5) each mounted on the susceptor 303(in FIG. 5), thereby forming an aluminum oxide film on each substrate314. During one vapor injection pipe is scanning one substrate, thesubstrate and the injected vapor substance are surrounded by thepartition walls 310 (in FIG. 5), thereby composing one reaction cell.Accordingly, each reaction cell (320 a to 320 d in FIG. 5) is almostchemically independent of the other.

[0048] The rotation speed of the vapor injection pipes 308 a.to 308 dpreferably has variable values that can be controlled by the positioncontroller 316 in FIG. 4. Further, the vapor injection pipes 308 a to308 d preferably approach the partition wall 310 with the nearest gaptherebetween during the above-explained process, as shown in FIG. 3.

[0049] In the above-explained process, an interval between differentperiods of providing different vapor substances is inverselyproportional to the rotation speed of the vapor injection pipes 308 a to308 d. That is to say, if the rotating speed of the vapor injectionpipes 308 a to 308 d are increased, time of one cycle composed of thedifferent periods is shortened such that a total processing time is muchshortened. In addition, because the flow of the vapor substance is notcontrolled by using valves, there exists no time delay resulting from aresponse time of the valves.

[0050] Returning to FIG. 3, when the deposition is finished, asubstrate-loading portion 302 sequentially unloads the substrates 314from the reaction chamber 300 and loads new substrates therein to mountthem on the susceptors 303.

[0051] As explained above, the semiconductor device fabricatingapparatus according to the preferred embodiment adopts the rotatingvapor injection pipes to achieve a short processing time. Instead ofrotating the vapor injection pipes, the susceptors may rotate but toprovide similar effect. In case of rotating the susceptors with thevapor injection pipes fixed, RF power may be applied into the reactionchamber via the vapor injection pipes, thereby activating the vaporsubstances such that plasma is generated in the reaction chamber.

[0052] The semiconductor device fabricating apparatus and the methodthereof according to the preferred embodiment enable a simultaneous ALDfor a plurality of substrates, in spite of using a relatively smallerreaction chamber. In addition, because the vapor substances are injectedfrom the rotating vapor injection pipes, the thin film can be moreuniformly formed. Accordingly, productivity and quality are improved.

[0053] It will be apparent to those skilled in the art that variousmodifications and variation can be made in the method of manufacturing athin film transistor of the present invention without departing from thespirit or scope of the invention. Thus, it is intended that the presentinvention cover the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. An atomic layer deposition method comprising:respectively loading a plurality of substrates into a plurality ofreaction cells, the plurality of reaction cells being disposed in areaction chamber; and alternately and repeatedly applying various vaporsubstances onto each substrate such that a thin film is formed on eachsubstrate, wherein a plurality of vapor injection pipes each injectingone of the vapor substances periodically scans over each substrate toapply the various vapor substances alternately and repeatedly onto eachsubstrate.
 2. The method of claim 1, wherein each substrate is heatedusing a heater disposed in the reaction chamber.
 3. The method of claim1, wherein RF power is applied to the vapor injection pipes such thatplasma is generated in the reaction chamber.
 4. A semiconductor devicefabricating apparatus comprising: a plurality of susceptors on which thesame number of substrates are respectively mounted; a reaction chamberisolating all the substrates on the plurality of susceptors from anexterior condition; a plurality of vapor injection pipes disposed overthe substrates, each vapor injection pipe relatively rotating withrespect to the substrates and periodically applying a vapor substanceonto each substrate; and a plurality of exhausting portion each disposednear a corresponding susceptor to exhaust a remaining vapor substanceout of the reaction chamber.
 5. The apparatus of claim 4, wherein avertical distance between the susceptors and the vapor injection pipesare variable.
 6. The apparatus of claim 4, further comprising aring-shaped heater disposed under the plurality of susceptors to heatthe substrates.
 7. The apparatus of claim 4, further comprising apartition wall separating each substrate from the others such that thevapor substance applied onto the substrate reacts with the samesubstrate only.
 8. The apparatus of claim 4, wherein the plurality ofsusceptors are fixed and the plurality of vapor injection pipes rotate.9. The apparatus of claim 8, further comprising a position controllercontrolling the rotation speed of the plurality of vapor injectionpipes.
 10. The apparatus of claim 4, wherein the plurality of vaporinjection pipes are fixed and the plurality of susceptors rotate. 11.The apparatus of claim 10, further comprising a position controllercontrolling the rotation speed of the plurality of susceptors.
 12. Theapparatus of claim 10, wherein RF power is applied to the plurality ofvapor injection pipes to activate the vapor substance such that plasmais generated in the reaction chamber.